#include <iostream>


using namespace std;


int main(int argc, char **argv){
    
    int num = 10;
    int * p1 = NULL, * p2 = NULL;
    p1 = &num;
    p2 = &num;

    cout << "num = " << num << endl;

    *p1 = 20;
    cout << "num = " << num << endl;

    *p2 = 30;
    cout << "num = " << num << endl;


    return 0;
}